Does anyone know if your followers drain charges of magical items they use? Do I need to trade them back and recharge?

Yes they do use charges. I've never seen them recharge on their own, I've always had to do it myself.

They get a LOT more charges out of it than you do (seemingly at least)

My friend gave Lydia the Axe of Whiterun and said she used it from level 20 to 30 without having to recharge it once (though it eventually ran dry)

So either she wasn't using it (using a default weapon or something else in lieu) or they get a LOT more use out of magic weapons than we do.

I equip my mage followers with staves..... seems to help them keep back at range and not get killed quite so much

Alright. Good information. Especially if they get more charges out of it.

II gave her my half charged electrical greatsword and every time I look at it, it looks like it's at the same charge level. So maybe they use them but like the man said, they must get more use out of th em.

What about stocking them with soul gems and adding soul trap weapons will that work...? i have a soultrap bow and sword i want to equip lydia with.... hrm...